Liquid crystal displays (LCDs) have been used widely, for example, for desk calculators, electronic clocks, personal computers, word processors, and instruments of automobiles and machines. Generally, such a liquid crystal display includes a polarizing plate for visualizing a variation in orientation of its liquid crystal, and the polarizing plate has an extremely large influence on display characteristics of the liquid crystal display.
As the polarizing plate, for example, a laminate formed in the following manner is used commonly. That is, a polarizer (polarizing film) such as a polyvinyl alcohol (PVA)-based film or the like is made to absorb a dichroic substance such as iodine, an organic dyestuff or the like and is aligned, and a protective film made from triacetylcellulose or the like is laminated on each surface of the polarizer. Particularly, there has been a demand for a polarizer that allows a liquid crystal display to have high brightness, good color reproducibility and excellent display characteristics.
However, in the liquid crystal display, particularly, in the case of using a backlight that emits polarized light, display unevenness occurs to decrease contrast uniformity, which has been disadvantageous. Particularly, in an image display, the achievement of high contrast entails a considerable degree of such display unevenness. For example, in the case where a normally black mode (in which a black display state is established in a state where no voltage is applied) is established as a liquid crystal mode, a considerable degree of display unevenness is observed in the view from an oblique direction at an angle of at least 30°, 40° and 60°.
Meanwhile, a polarizer is produced generally by the following method. That is, a hydrophilic polymer film is conveyed by means of a guide roll so as to be impregnated in a swelling bath for swelling, then is impregnated in a dyebath containing a dichroic substance for dyeing, and further is stretched while being impregnated in a crosslinking bath. Previously, for example, JP2002-28939 A and JP2002-31720 A have disclosed as the hydrophilic polymer film PVA films having improved thickness uniformity. However, even when such a film is used, there is a possibility that a polarizer as a finished product has a variation in retardation and a variation in the content of a dichroic substance.